Cameras are commonly employed for position measurements in applications where high accuracy positioning in a two-dimensional image plane (x and y planes) is necessary. These applications include, for example, alignment of a mask and substrate in preparation for patterning processes in the production of ultra-high definition displays and high pixel density screens for mobile devices.
Currently, in these types of applications, distance measurements along a depth axis (z plane) are typically performed using laser distance sensors, confocal sensors or contact sensors. These sensors may add substantial cost and complexity to current manufacturing processes.
Accordingly, depth measurement apparatus and methods with high accuracy and without the complexity and costs involved with the use of existing sensors are desired.